热光源产生贝塞尔光束的理论与实验

利用热光源获得了近似贝塞尔光束。对多波长光波同时入射轴棱锥的情形进行分析和数值模拟,结果显示轴棱锥后会形成近似贝塞尔光束,但受光场非相干叠加的影响截面光强对比度降低。实验采用卤素灯杯作为产生贝塞尔光束的热光源,针对热光源相干性差的特点设计出一套光学系统,提高光波的空间相干性,再使光波平行透过轴棱锥得到了近似贝塞尔光束。将实验结果与数值计算对比,发现实验所得贝塞尔光束的特性与理论基本吻合,但最大无衍射距离较理论计算所得的短,并对此进行了分析。

Theory and Experiment of Bessel Beam Generated by Thermal Light Source

Bessel-like beam is generated by using thermal light source. The incident condition for the light waves with multi-wavelength passing through axicon simultaneously is analyzed and simulated. The results show that Bessel beam can be generated behind the axicon, but the contrast of the cross section light intensity drops because of the incoherent superposition of the multi-wavelength light waves. In our experiment, halogen light cup is used as thermal light source for generating Bessel beam. A set of optical system is designed to improve the spatial coherence of the light waves, and the Bessel-like beam is generated after the light waves passing the axicon. Comparing the experimental result with the numerical simulation, it is found that Bessel beam obtained from experiment is basically in accord with the numerical calculation. Besides the maximum diffraction-free distance is shorter in the experiment, which is analyzed at the end of the paper.